Mesoscale Discussion 1699

Issued

Sep 7, 2021, 3:40 AM EDT (07:40 UTC)

Expired

Sep 7, 2021, 6:15 AM EDT

In force

3 hr

Issued by

the Storm Prediction Center

Concerning

Severe potential...watch unlikely

Chance of a watch

20%

The Duluth radar (KDLH), 154 km from the middle of the area, began a volume at 07:43 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

012 
ACUS11 KWNS 070740
SWOMCD
SPC MCD 070740 
WIZ000-MIZ000-MNZ000-071015-

Mesoscale Discussion 1699
NWS Storm Prediction Center Norman OK
0240 AM CDT Tue Sep 07 2021

Areas affected...Portions of far eastern MN...northern WI...and the
western U.P. of MI

Concerning...Severe potential...Watch unlikely 

Valid 070740Z - 071015Z

Probability of Watch Issuance...20 percent

SUMMARY...An isolated threat for hail and strong/gusty winds may
exist with storms moving eastward early this morning. Watch issuance
is unlikely at this time.

DISCUSSION...Isolated to scattered storms have recently moved from
eastern MN into northern WI and the western U.P. of MI early this
morning. Most of this convection has been occurring to the north of
a warm front, and likely remains slightly elevated above a
near-surface stable layer. Still, winds strengthen quickly above the
surface per recent VWPs from KMPX, and a strong low-level warm
advection regime will likely support this activity for at least the
next few hours as it continues eastward. A reservoir of moderate to
strong MUCAPE should exist ahead of these storms across parts of
northern WI, and deep-layer shear appears adequate for some updraft
organization. Given the mainly linear nature to a cluster of storms
crossing into the western U.P. of MI from far northern WI, they may
be capable of producing isolated strong/gusty winds from any
convective downdrafts that can reach the surface. Farther west along
the MN/WI border, other more isolated cells that have recently
developed could produce marginally severe hail with the steep
mid-level lapse rates present over this area. Regardless, all of
these storms should have a tendency to remain slightly elevated
given the presence of considerable convective inhibition noted on
recent mesoanalysis. Therefore, the overall severe threat in the
short term will likely remain too isolated/marginal for a watch.

..Gleason/Edwards.. 09/07/2021

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...MQT...GRB...DLH...ARX...MPX...

LAT...LON   45519338 45789337 46089264 46349046 46858946 47048903
            47138863 46928828 46188843 45308868 44908954 44929116
            45209244 45519338

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The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.